A GRK2 and GRK3 inhibitor (IC50s = 18 and 5.4 nM, respectively); selective for GRK2 and GRK3 over GRK1, GRK5, GRK6, and GRK7 (IC50s = 3,100, 2,300, >30,000, and 25,000 nM, respectively), as well as ROCK-2 and PKCα (IC50s = 1,400 and 8,100 nM, respectively); induces cAMP accumulation in HEK293 cells expressing human β2-adrenergic receptors (EC50 = 10 μM); inhibits electrical field stimulation-, norepinephrine-, phenylephrine-, endothelin-1-, and U-46619-induced contractions in isolated human prostate strips at 50 μM,